Several devices are known to the art by means of which healing of bone tissue is promoted by electrically stimulating the bone tissue with the aid of one or more electrodes applied to the fracture point of a broken limb, these devices including means whereby an electric current or an electric voltage can be applied to the electrode.
Such devices and electrodes are normally used to avoid the necessity of carrying out surgery on the damaged bone. To this end it is known to affix one or more electrodes in the region adjacent the fracture surface and to connect the electrodes to an electrical stimulating device, located externally on a fractured limb being treated, or on a plaster cast placed therearound.
A variety of such electrodes, which are affixed to bone tissue and connected to a source of electric current or voltage for the purpose of stimulating a bone healing process (osteogenesis), are known to the art.
Electrodes used within the medical field for this purpose can be divided into two separate categories, each relating to the nature of the tissue to which electrodes are to be applied and the manner in which they are used. Thus, electrodes of the first category are particularly designed for insertion into soft tissue and there to be firmly and reliably held in good electrical contact with the soft tissue, normally muscle tissue, these electrodes normally being used to evaluate muscle tension etc.. The electrodes belonging to the second category are particularly designed for attachment to bone tissue or hard tissue, so as to be firmly seated in good electrical contact with the hard tissue while being insulated from the soft tissue, in order to stimulate osteogenesis.
The present invention relates to the second category of electrode.
The U.S. Patent Specification No. 3,842,841, which relates to an electrode of this second category, discloses the use of an external anode which is secured to the outer surface of the skins and a cathode which comprises a long rigid stainless steel wire covered with an electrically insulated material, such as polytetrafluoroethylene. This steel wire is pressed through the skin, i.e. percutaneous insertion, whilst screening the damaged area with X-rays (radioscopy), and pushed into the bone close to a fracture or area of diseased bone to be treated.
It is also known to use a hand drill to assist the insertion of these rigid electrodes some short distance into the bone tissue, so that the electrode tip is firmly seated therein.